Overtravel protective system



July 20, 1926. 1,593,395

J. EATON OVERTRAVEL PROTECTIVE SYSTEM Filed Feb. 10, 1926 Inventor: John Eaton,

H is; Atto whey Patented Ja 20, 1926.

UNITED STATES PATENT o Ficn 301m m'ron, or

OVERTRAVEL PROTECTIVE SYSTEM.

SCHENECTADY, NEW YORK, ASSIGNOR. TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

Application filed February 10, 1926. Serial No. 87,472.

The invention relates to the automatic checking of the motion of moving bodies when they have passed a predetermined position, and to the reestablishment of control of such motion. It is" especially applicable to elevators, hoists, and other lifting and lowering apparatus. Such devices are usually provided with means for reventing the car, bucket, or hoisting hook, rom travelling too far, either ascendin or descending. An automatic, self-resetting switch which stops the hoisting motor or drum is in common use for this purpose. But the means for preventing overtravel, whatever form they may take, may get out of order occasionally and permit the car or other load to overtravel until it is stopped by some other means, or a wreck occurs. An additional protective device is, therefore, often provided to stop the apparatus when the first pro tective device fails to do so. This additional safety device may consist merely of a second automatic switch for stopping the driving motor or drum. But it has been recognized that means should 'also be provided for making known that the first safe ty device has failed. And it has also been recognized especially in the case of the ordinary passenger elevators, that this means should act in such a way as to lead -the operator of the elevator to bring the trouble to the attention of some one who will correct it. To secure this result the second automatic switch has been so constructed in some cases that it has to be reset before the elevator can be moved, and this second switchhas been so constructed -or located that it could not be reset by the ordinary operator. The elevator was thus put out of use until some one who could reset this switch was .called. This person would presumably see that the trouble with the first switch was removed. Putting the elevator out ofuseuntil a mechanic or manager can be obtained wouldbe in many sitnations an intolerable annoyancelto users. But if the protective devices are such as can be-reset by the elevator operatorhe may not notify the proper person been a failure of the apparatus to properly function. l

'One object of my invention is to automatically stop the car or other moving apthat there has 7 paratus when overtravel occurs and to automatically restore control to the operator after a predetermined time. Another object is to afford some indication, after control has been restored, that there has been difficulty. Another object is to provide such an indication in a form which will strongly tend to cause the operator or others to bring the fact that there has been trouble to the attention of the person who should be notified thereof but which will not render the apparatus useless until this notice is given and the trouble corrected.

In the preferred form of my apparatus which is illustrated and described herein, a car or hoist is automatically sto ped when it has passed beyond a first sa ety device (not shown) orother limit of travel which has been fixed for it. It is then automatically held at rest out of the control of the operator for a limited time. After this limited time has expired, control is automatically restored to the operator, but he can drive the car thereafter only at reduced speed until certain apparatus is operated or reset by someone who is specially qualified for such work. The continued operation at reduced speed will act as a strong inducement to. the operator to report the trouble. If he does not do sothe slower service will lead to complaint by the patrons. This operation of the elevator at reduced speed is an indication of trouble apparent the car. in operation to everyone who sees and continuing'until the said certain apparatus is operated or reset.

The mechanism which I have invented for accomplishing these results is illustrated in .its preferred form in the accompanying drawing, in which the car 1 is raised and lowered by the drum and cable 2, and driving means 2. The line 3 su plies current through the controller 4, Eli switches 5,and conductors 6, 6', 6

vator. All of these elements, as the diagrammatic illustration thereof shows, may be of known construction.

Current in the conductors 10 or 11 closes one or the other of the operating switches If) to send current in one direction or the other in conductors 6", 6" and 6, and cause the car. to ascend or e operating and 6, to control the ordmary operation of the eledescend. Each of the.

switches 5 automatically opens upon the cessation of current in its corresponding conductor 10 or 11 When both of these switches are open the car is at rest. In normal operation, the operating circuits for the switches 5 lead from the line 3 through conductor 6, controller 4, conductor 10, or con- 'ductor 11, conductors 12 and 12, switch 7,

conductor 13, switch 8 and conductor 14, back to line 3.

lVhen the car 1 descends below the ordinary first safety switch, if one is used, or in any event below the point fixed upon as the limit of its ordinary travel, the switch 7 is thrown. This may be accomplished by a projection 9 on the ctr. /Throwing the switch 7 breaks the path through conductors 10 or 11, 12, 12 13 and 14, and thereby causes both switches 5 to be/ open, stops the car, and makes it impossible for the operator to start the car in either direct-ion for the time being. The throw of the switch 7,

I the car passes start it for the of any other suitable construction.

through the resistance 6.

moreover, completes a path from line 3 through conductor/15, time relay 16, conductors17, 18 and14, back to line 3. The time relay 16 may be of a known thermostatic form as indicated on the drawing, or Upon the lapse of a predetermined time after the throw of switch 7, which time may be as short or long as desired, time relay 16 closes a branch circuit 22 from conductor 15 to conductor 17 through the solenoid of switches 20 and 21, thereby closing switch 20 and opening switch 21. The closing of switch 20 establishes a path from the line 3, through the controller 4, conductors 10 or 11, and conductors 12, 12 and 14, back to the line 3. This restores control of the car to the operator. He can now start and stop it in the usual manner by means of the hand lever of controller 4.

ut the operating current in the conductors 6 and 6, which normally passed mainly through the conductors 6, is now forced by the opening of switch 21 to pass entirely The resulting reduction in the magnitude of the current in the conductor 6 reduces the speed of the car to a'fraction of the speed at which it operated before the switch 7 was thrown. Exce t for this reduced speed the car can now e o erated throughout its entire range in the or inary manner.

The switch 8 is in all respects similar to.

the switch 7 except that it is-operated when above the limit set for its ascending journey in normal operation. Like switch 7, the switch 8' when thrown first breaks the path from the controller 4 through conductors 10 or 11 and conductors 12, 12", 13 and 14, causing the car to stop and making it impossible for the operator to time being. Like switch 7,

the switch 8 when thrown establishes a path through conductor 15, time relay 16, conductors 17, 18 and 14, and thereby causes the time relay after a predetermined period to complete a path 22 through the solenoid of switches 20 and 21 and thereby close switch 20 and open switch 21. Here as before, the closing of switch 20 restores control to the operator but the opening of the switch 21 makes it impossible for him to run the car at a speed greater than some predetermined fraction of its normal speed.

Uponany overrunning of the elevator and the consequent throwing of switch 7 or switch 8, the elevator is inoperative only during the time required for the action of the time relay 16. After this relatively short delay, the elevator continues to serve its intended purpose though at a low speed. Operation continues at this low speed until the protective apparatus is reset. The resetting of the protective apparatus comprises the return of the time relay 16 and switches 7. 20 and 21 to their normal positions, though all of these elements except the switch 21 may be self-resetting if desired. After all of these devices have been reset the car can be run once more at its normal speed and the protective. devices are ready for another operation as soon as the car again overruns its proper journey.

In order to insure that the elevator operator does not himself reset these devices, and fail to inform some more res onsible person that the car has overrun, t e time relay 16 and switches 7, 8, 20 and 21, or, some one or more of these elements, including the switch 21, may be so located or constructed that the cannot be reset except with the aid of akey, or some other special means of access or, knowledge, which the operator would not have. The inabilit to operate the elevator at normal speed a ter either of the switches 7 or 8 has been thrown and prior to the resetting of the protective apparatus will naturally cause a report to be made to someone who can restore the protective apparatus to its .normal condition, and who will presumably at the same time see that the trouble which led to the overrunnin .is corrected.

Tie reason for using the time relay 16, instead of sending current through the solenoid of switches 20 and 21 to operate these switches immediately upon the throw of either of the switches 7 or 8, is to brin home to the operator that he has passed yond the range of normal operation and that he should start the car in the opposite direction when control thereof is restored to him.

The invention is obviously not restricted in its application to lifting and lowering devices, but is applicable generall where it is: desirable to x a limit beyon which a .movinglbody shall not normally pass, and esp'ecia y to any case of reciprocating monecessarily require the production limit of motion either at one or both ends of,

a path which might be exceeded if some special apparatus were not supplied. It is likewise evident that the invention does not of all of the results or the use of all of the features which are disclosed in the drawing and specification, and does not depend on the use of the particular forms of elements or arrangement of circuits indicated on the drawing, but will be present in its broader aspects in any structureor system which comes within the definitions of the invention which are set forth by the appended claims.

. W hat I claim as new and desire to secure by Letters Patent of the United States, is:

1. In combination, a movable means and means for causing the motion thereof, a controller therefor, means automatically operated when .the motion of the movable means exceeds a certain limit to change the motion of the movable means, render the controller inoperative for a time, and there- ?fter to restore operativeness to the control- 2. In combination, a movable means and meanafor causing the motion thereof, a controller therefor, means automatically operated when the motion of the movable means exceeds a certain limit to change the motion of the movable means, render the controller inoperative for a time, and thereafter to restore operativeness to the controller, and

restrict the speed of the moving body.

3. In combination, a movable means and means for causing the motion thereof, a controller therefor, means automatically operated when'the motion of the movable means exceeds a certain limit to change the motion of the movable means, render the controller inoperative for a store operativeness to the controller, and restrict the speed of the moving body until the apparatus is subjected to a special manipula-tion.

4. In combination, a movable means and -means for causing the motion thereof, a controller therefor, a-time limit device, means for autmatically stopping the movable means, rendering the controller inoperative, and initiating the action of the time limit device.

' when the movable means has passed a certain position, and means actuated by the time limit device for rendering the controller operative after the expiration of a definite time.

' '5. In combination, amovabe means and means for causing the motion thereof, a con-, troller therefor, a time limit device, means the movable rendering the controller inoperative, and initiating the action of the time limit device, when the movable means has passed a certain position, .and means actuated by time and thereafter to re-' the time limit device for rendering the controller operative after the expiraticn'of a definite time,and for restricting the speed of the moving body until the time limit device and its associated means have been reset.

6. In combination, a movable means and means for causing the motion thereof, a controller therefor, a time limit device, means for automatically stopping the movable means, rendering the controller inoperative, and initiating the action of the time limit device, when the movable means has passed a certain position, and means actuated by the time limit device for rendering the controller operative after the expiration of a definite'time, and for restricting the speed of the moving body until the time limit device and its associated means have been reset, said time limit device and its associated means being incapable of ready resetting by unauthorized persons.

7. In combination, a member designed to be normally moved to a certain point and back again, and means for causing its n10- tion, a manually operated controller therefor, an electric switch which is automatically thrown when said member reaches a certain position beyond said point to which it is normall designed to move, a time relay, a circuit which is controlled by said throw of said switch to stop the motion of said member and render said controller inoperative, a circuit which is controlled by said throw of said switch to initiate the. action of the time relay, a circuit which is closed by said time relay after the expiration of a certain time, means actuated by the closing of the last mentioned circuit to render' the controller operative.

8. In combination, a member'designed to be normally moved to a certain point and back again,- ,and means forcausing its motion, a manually operated cont-roller therefor, an electric switch which is automatically thrown when said member reaches a certainposition beyond said. point to which it is normally designed to move, a time relay, a

circuit which is controlled by said throw of said switch to stop the motion of said member and render said controller inoperative,

a circuit which is controlled by 'said throw of said switch to initiate the action of the time relay. a circuit which is closed by said time relay after the expiration'of a certain time,

for, an electric switch which is automatically thrown when said member reaches a certain position beyond said point to which it is normally designed to move, a time relay, a circuit which is controlled by said throw of said switch to stop the motion of said memher and render said controller inoperative,

a circuit which is controlled by said throw of said switch to initiate the action of the time relay, a circuit which is closed by saidv relay after the expiration of a certain time, means actuated by the closing of the last mentioned circuit to'render the controller operative, and to reduce the speed at which the movable member is capable of moving to a speed substantially below its normal speed, said time relay and associated devices being incapable of ready resetting by unauthorized persons to render normal speed possible.

10. An elevator comprising a car and electrical lifting, lowering and controlling apparatus therefor, an electric switch which is automatically thrown when the car passes eyond one of its normal limits of travel, a circuit which is controlled by the throw of said switch to stop the car and render the controlling apparatus therefor inoperative, a circuit which is controlled by said throw of said switch to actuate a time relay, a circuit which is controlled by said time relay after a certain time to render the car controlling apparatus operative, and to limit the speed at which the car can be operated to a lower speed than the normal until the apparatus is subjected to a further manipulation to that end which cannot be readily performed by unauthorized personsQ 11. An elevator comprising a car and electrical lifting, lowering and controlling apparatus therefor, an electric switch which is automatically thrown when the car passes beyond one of its normal limits of travel, a circuit which is controlled by the throw of said switch to stop the car and render the controlilng apparatus therefor inoperative,

direction, a single conductor constituting one portion of each of said circuits, two switches in said conductor, one at each end of the path of travel of the reciprocating means, means whereby the passage of the reciprocating means beyond either of the intended normal limits of its travel will throw one of said switches to open said parallel circuits and thereby bring,,the reciprocating means to rest and also render the controller inoperative.

13. In combination, means designed to be normally reciprocated within certain limits and means for driving the same, a manually operated controller therefor, parallel circuits controlled by said controller for starting and stopping the driving means in either direction, a single conductor constituting one portion of each of said circuits, two switches in said conductor, one at each end of the path of travel of the reciprocating means, means whereby the passage of the reciprocating means beyond either of the intended normal limits of its travel will throw one of said switches to open said parallel circuits and thereby bring the reciprocating means to rest and also render the controller inoperative, a time relay, an operating circuit therefor, said circuit extending adjacent the switches at the ends of the path oftravel of the reciprocating means and controlled by the throw of either of said switches, a second single conductor connecting with each of said parallel starting and stopping circuits, a normally open switch in said second single conductor, a circuit closed by said time relay at a predetermined time after the closing of its operating circuit to close the a circuit which is controlled by said throw of said switch to actuate a time relay, a circuit which is controlled by said time relay after a certain time to render the car controlling apparatus operative, and a circuit which is controlled by said time relay after a certain time to reduce. the possible speed of the electrical lifting" and lowering ap paratus to a value substantially below its normal speed, the resetting of the apparatus for making possible a return ,to normal speed being incapable of ready' accomplishment by unauthorized persons.

12. In combination, means designed to be normally reciprocated within certain limits and means for driving the same, a manually operated controller therefor, parallel circuits controlled by said controller for starting and stopping the driving means in either switch in, said second single conductor and thereby render the controller operative.

14. In combination, means designed to be normally'reciprocated within certain limits and means for driving the same, a manually operated controller therefor, parallel circuits controlled by said controller for starting and stopping the driving means in either direction, a single conductor constituting one portion of each of said circuits, two switches in said conductor, one at each end of the path of travel of the reciprocating means, means whereb the passage ofthe reciproeating means eyond either of the intended normal limits of its travel will throw one of said switches to open said parallel circuits and thereby bring the reciprocating means to rest and also to render the controller inoperative, atime relay, an' operating circuit therefor, said circuit extending adjacent the switches at the ends of the path of travel of the reciprocating means and controlled by the throw of either of said switches, a sec- 0nd single conductor connecting with each time relay at a predetermined time after the closing of its operating circuit to close the switch in said second single conductor and thereby render the controller operative, 6 an operating circuit for the driving means, and means actuated by the closing of the circuit controlled by the time relay and putv ting resistance into the operating circuit for the driving means and thereby reducing the speed of the reciprocating means.

In witness whereof, I have hereunto set my hand this 8th day of February, 1926.

' JOHN EATON. 

